Thread: Socket connection problem

  1. #1
    Registered User
    Join Date
    Oct 2010
    Posts
    2

    Socket connection problem

    Hello There, I am trying to change a simple client code that will retrieve the web pages from any web site using TCP sockets. It fails in the connect function.
    When I made the code run on my m/c (with a server), it worked fine but it doesnt create connection to other web sites like google and all. I have a similar Java code that works but don't know where exactly am I going wrong.

    I am running it on a 64 bit AMD Turion X2 with Ubuntu 9.10

    Code :

    #include <stdio.h>
    #include <stdlib.h>
    #include <string.h>
    #include <unistd.h>
    #include <arpa/inet.h>
    #include <sys/types.h>
    #include <netinet/in.h>
    #include <sys/socket.h>
    #include <netdb.h>

    #define MAXRCVLEN 500
    #define PORTNUM 80

    int main(int argc, char *argv[])
    {
    char buffer[MAXRCVLEN + 1];
    int len, mysocket;
    struct sockaddr_in dest;
    int ret;
    struct hostent * hinfo;
    char * sname;
    if (argc > 1)
    {sname=argv[1];}
    else
    {sname="cprogramming.com";}

    mysocket = socket(AF_INET, SOCK_STREAM, 0);

    memset(&dest, 0, sizeof(dest));
    dest.sin_family = AF_INET;

    hinfo = gethostbyname(sname);
    if(hinfo == NULL) {printf("getbyname failed!\n");}

    dest.sin_addr.s_addr = inet_addr(hinfo->h_addr);

    dest.sin_port = htons(PORTNUM);

    ret = connect(mysocket, (struct sockaddr *)&dest, sizeof(struct sockaddr));
    printf("Connection status:%d\n", ret); /* ret is -1 here*/

    len = recv(mysocket, buffer, MAXRCVLEN, 0);
    buffer[len] = '\0';

    close(mysocket);
    return EXIT_SUCCESS;
    }

  2. #2
    Registered User
    Join Date
    Oct 2010
    Posts
    2
    well, my friend helped me out. i made the following change
    As was:
    dest.sin_addr.s_addr = inet_addr(hinfo->h_addr);
    Changed To:
    dest.sin_addr = *(struct in_addr *)(hinfo->h_addr);

    Now the connection is working but recv gets hanged. Probably need to send some formatted request to server. But why dont we need to do that request in Java?

  3. #3
    and the hat of int overfl Salem's Avatar
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    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
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